From the windows of Coach Steve Fisher’s corner office at San Diego State, he can look across the street to the box office at Viejas Arena. When he arrived at work Monday morning, there was a line of students.

There was still a steady line Tuesday morning, students waiting to claim their allotment of 2,500 tickets for the men’s basketball game the following night. And then there was no more line.

No more tickets.

Now consider that temperatures hovered around freezing and that the spring semester at SDSU doesn’t begin until Thursday, which meant students had to make a special trip to campus to pick up a ticket.

Which meant one thing: The Rebels.

SDSU’s sports teams have largely existed without a natural rival, without a USC to their UCLA, without an Alabama to their Auburn, without a Harvard to their Yale. UNLV, in basketball at least, has filled that void in recent years and now, suddenly, it could vanish like breath on a cold winter morning.

SDSU officials are expected to announce in the coming days or weeks a decision on conference affiliation for next season. They could stay in the Mountain West and have twice annual basketball games against the Rebs, or they could continue as planned to the Big East in football and Big West in basketball.

The consequences have not escaped the players.

Chase Tapley was talking about their most recent meeting against UNLV, a wrenching two-point loss in Las Vegas last February that ended SDSU’s streak of six straight wins in the series: “We still had that game in hand and just came up short. We just want to reverse it back on them and get a victory on them.”

And then he threw this in: “We want to end the rivalry right if there’s a change in leagues.”

Wednesday night’s game at soldout Viejas Arena matches the 14-2 Aztecs against the 14-3 Rebels. The nation’s No. 15 team in the Associated Press Top 25 against No. 23 in the USA Today coaches poll. The team picked to win the Mountain West with 153 points from the preseason media panel against the team picked to finish second with 151 points.

But it goes deeper than that.

“We recruit the same kids,” SDSU associate head coach Brian Dutcher said. “It’s kids that we tried to get that they got over us, or maybe someone they wanted that we were able to get. We’re really familiar with each other, players and coaches. It makes for a very competitive environment.”

Bryce Dejean-Jones and JJ O’Brien, for instance. Both were transfers. Both had UNLV and SDSU as their two finalists. UNLV got Dejean-Jones; a few days later, the Aztecs got O’Brien.

“Part of it also is the great games we’ve had with them over a number of years,” Fisher said. “And it hasn’t mattered who was the favorite. We’ve had some terrific games with them, and I think everybody likes that.”

Terrific, and tight. The last three have been decided by two points, the last five by six points or less.